The present invention relates to radio tuners and more particularly to an arrangement for providing current to a lamp of the tuner indicator.
In a common type of radio tuner, an indicator is moved along a linear scale by means of a cable which responds to rotation of a tuning control knob. Attempts have also been made heretofore to mount a lamp to the indicator so that the position of the indicator on the scale will be readily illuminated. In such prior art devices, the electrical connection to the lamp has generally been made by a special cord which follows the motion of the lamp. The principal disadvantage of this arrangement is that the possibility exists that the cord can bind on some portion of the radio housing and hence impede tuning or possibly snap. In addition, the constant flexing and unflexing of the cord can result in the cord breaking at solder or crimp joints.
In order to overcome the shortcomings of the arrangements described above, attempts were made to provide current to the lamp through the indicator drive cable with the lamp also making electrical contact with a return rail mounted adjacent the scale. Various modifications in this design were also proposed such as the use of two rails adjacent the scale, however, all these designs require that a sliding electrical contact be made to insure a closed path to the lamp regardless of the specific position of the indicator at any particular time. Thus, these prior art devices required at least one and, in some cases, two sliding electrical contacts. The disadvantage of these arrangements is that the sliding contact represents a source of high frequency noise in the output of the radio. Further, the design of such devices is relatively complicated.
In view of the above, it is the principal object of the present invention to provide an improved arrangement for providing current to a radio tuner indicator lamp which overcomes the objections of the prior art.
A further object is to provide such an arrangement which is relatively simple and inexpensive to incorporate into a tuner.